Flanges, which are well known in the art, are generally required in installations having conduit or pipes for connecting valves, pumps, meters or other equipment which may require periodic servicing or replacement. Many flanges are formed integrally with the valve or pump. Those of concern in the instant invention are of the hubless type which are removably mounted to the valve, pump or other equipment. The particular method of mounting the hubless flange to the equipment is not part of the present invention.
Hubless (replaceable) flanges are especially useful since they lend a great deal of versatility to expensive equipment by enabling use of such equipment in a number of different mounting arrangements. Consequently use of different size flanges and bolt hole configurations is economically advantageous to both the manufacturer and the user. For example, a hubless flange enables use of a valve in a number of different types of pipeline installations by simply replacing the flange on the valve body.
Another advantage accrues where the material from which the equipment is fabricated is especially expensive or, as is quite common, is of limited strength and durability not suitable for the rough treatment and forces encountered during installation or removal. The flange may be constructed of extremely durable material and coupled to the body of the equipment by means of a split key arrangement or the like and, therefore, be substantially immunized from the adverse effects of installation and removal.
Hubless flanges are generally annular or ring-shaped and of substantially rectangular cross section. The type of material and actual dimensions of the flange are, of course, dependent upon its intended service and the accompanying stresses and strains to which it will be subject. In corrosive environments involving pressures up to about 1400 p.s.i., flanges may be made of high quality metals such as CF8M stainless steel or WCB carbon steel. Such materials can be expensive and there is a definite need to make flanges using them cost effective, that is capable of meeting service specifications with a minimum amount of material. The present invention teaches a hubless flange construction and design which yields substantial savings in material for equivalent performance over prior art hubless flanges. As will be seen, the tangential stress in the material is critical. In a ring shaped flange, these stresses are directed tangentially to annular fibers in the flange and perpendicular to the conventional forces applied during clamping.